This is a small turbo (S363) on an LS1 with a stock cam. 499whp and all of the torque.
Go with a smaller turbo and less boost. You'll gain tons of low/mid range torque.

 

2500lbs with me in it. Corner speeds is kind of a loaded question. Depends on the corner, going through some esses were it would stay spooled up could be 120-130+mph. Coming out of a 1st gear tight turn is a dog because it’s not spooled up. That’s why I was curious about going NA to help the drive off the slower corners. But smaller turbo is the route to go with this engine. Buttonwillow we were carrying around 150-155 mph down into t1, Laguna Seca was 143 mph into t1. The car is a rocket once it gets rolling.

what do you think about the s372?

 

S372 is an option but I would go with a billet wheel if you're going to stick to anything larger than an S366.
VS Racing has a ton of billet turbos in the 62-72mm range for less than $700 but I don't like the turbine choices much.

A gen 2 billet 7875 with the 1.25 A/R T4 would pick up noticeably on your setup in the mid range but might not give you that same low/mid grunt, although at your weight that might be good for traction.

 

It would suck to have the car falling on its face at 5500 if he needs 7800 RPM though.

 

That was a bone stock (cam and all) LS1 with an S363 that was dumping timing up top.

An LS6 cam 5.3 with good valve springs, 112 fuel with plenty of timing up top won't have the same shortfall.
An S363 isn't the ideal turbo for that much RPM, but it'll provide enough torque out of corners that he can still make power up to 6600-6800.
It depends on overall needs/goals. That why I recommended somewhere in between the S362 and V2 7875 depending on just where he wants to move the power and how much he needs to change the curve.

Anything is better than those On3 cast PT88 clones.

 

I think undersizing a turbo is underrated. When you want power at 2k to 7k there are benefits to keeping it smaller. The area under the curve is nuts. There's a reason many of the factory turbo or twin turbo cars under size their stuff and they still rev to 7k. Sure it falls off up top but your power curve is so much more fun to drive.

 

Agree but even 6800 is low, even for a street car. I'd hate to be that RPM limited in something fun to drive on a road course.

Depends, you can make stuff capable of silly power spool within a few hundred RPM of that S300. The gen 2 7875 spools a lot faster then his current turbo and can make pretty decent jams. Looking at that chart above its probably not even that far apart and make a ton more power. Just depends if you want power from 3000-6000 or 3500 to 7500.

 

3500 sounds vastly better than it coming on at 4800 or whatever it was. One of the biggest hurdles with this car is tire size. It’s on a 23” tall tire, but it has a 4 speed dog box in it. So no over drive = revving the **** out of it for MPH. My tuner is the one that recommended the s372sx-e since it’s a billet wheel. Anything is going to be better than the on3 I think, don’t mean to knock it. It worked well when we were doing 1/2 mile drag stuff because it was just wound up the whole time

 

Apples to apples, only changing turbos, tuning only gets you so far. He's running an on3 88mm which obviously isn't made for power down low. Also have to take into account A/R differences which will shift the power curve besides the wheel size.

 

The S372SXE wouldn't be a bad option at all being a 72/73, only real downfall is its close to double the price of the next gen 78/75 but may gain you a few more RPM. Seen some guys run a single S369 in the past which I believe is same turbine as that S372, 69/73 vs a 72/73.

 

Ls7. It was built to do exactly what you are doing. Less weight up front and you may be able to lower the engine/trans with the dry sump setup for a lower CG. Could easily get 600whp and instant torque off corners.

 

And a used one costs 4 to 5 times his current setup.

 

At least, cheapest LS7 I've seen for sale is 10x what I pay for 5.3's. I've also seen fancy headed, solid roller, built to the moon LS7's not make what a SBE 5.3L does on low boost. Bang for the buck horsepower wins to me! Plus not a huge weight difference between an LS7 and an aluminum 5.3.

 

Sorry to revive the dead here. Just looking for some theoretical numbers here. I decided to go na for several reasons. So I was hoping for some help guessing numbers before I pull the trigger.

3.903 bore +12cc dome piston
PRC as cast heads 252cc
750lbs dual springs
1.72 roller rockers
238/242 .600"/.600" 113lsa
7800-8000 rpm

The engine has ARP main and head studs, H beam rods in it now, and the car now also has an Aviaid dry sump

Fast 102 intake is arriving on Monday.

I will either be switch to e85r or continuing to run 112 race gas.

Thanks guys

if anyone wants a s372sxe with a 60mm wastegate flange on the turbine housing and setup for 3” v band downpipe let me know. Lol bought all the stuff just to mock it all up and sell it.